Fairy-tale trespasser (10)
I believe the answer is:
'fairy-tale trespasser' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for goldilocks that I've seen before include "Trespasser" , "Fairy tale porridge thief" , "Visitor for three bears" , "Plant" , "fairly shocked girl" .)